Appliances of the aforementioned kind include safety razors and toothbrushes. Other such appliances could include massaging devices. A toothbrush including a vibration mechanism is described in GB-A-2250428, and in U.S. Pat. No. 4,744,124 there is described a toothbrush including a sound generator which is switched on by pressing the brush head against the teeth. In GB-A-2258922 there is proposed a personal care apparatus such as an electric toothbrush with a capacitive sensor in the handle so that the motor is turned on when the toothbrush is picked up in the hand.
A safety razor generally comprises a handle and a blade unit carried on the handle and including at least one blade with a sharp cutting edge. In the course of shaving, the blade unit is applied against the skin and the blade or blades are moved across the skin so that the sharp cutting edges engage and cut through the hairs protruding from the skin. The blade unit can be fixed on the handle with the intention that the entire razor should be discarded when the cutting edges have become dull and are no longer capable of providing a comfortable shave. Alternatively the blade unit may be removably mounted on the handle so that the blade unit can be replaced by a new blade unit when the sharpness of the blades has diminished to an unacceptable level. Replaceable blade units are often referred to as shaving cartridges.
The majority of safety razors currently marketed are operated and used entirely manually. Nonetheless electrical devices can be incorporated in safety razors and it is known to include an electrically driven vibration mechanism which is operable to vibrate the razor, it having been observed that such vibration can have a beneficial effect on razor performance. A simple and convenient vibration mechanism consists of an electric motor with a weight mounted eccentrically on its output shaft. The vibration mechanism and a battery for providing electric power to the motor can be conveniently housed in the razor handle. Examples of previous proposals for such razors are those described in EP-A-0885698, U.S. Pat. No. 3,611,568, U.S. Pat. No. 5,299,354, U.S. Pat. No. 5,214,851, U.S. Pat. No. 5,046,249 and U.S. Pat. No. 6,481,104B1. Although vibrating the razor can enhance the razor performance during actual shaving, it is not without drawbacks. Many razor users dislike the feel of a vibrating razor held in the hand and this has led to attempts to design the razor handle so that the vibrations are concentrated at the blade unit and are not transmitted to the part of the handle generally gripped in the hand of a user, as disclosed in U.S. Pat. No. 5,214,851, U.S. Pat. No. 5,046,249 and U.S. Pat. No. 6,481,104B1.
In EP-A-0906814 there is proposed a safety razor including a piezoelectric element on the razor head for producing a signal dependent on forces exerted on the razor head. It is suggested that a voltage produced in dependence upon the output signal could, inter alia, activate a motor to produce a motion, such as vibration, but the purpose of the vibration is not stated and it could be only to indicate to a user that too much force is being applied or that the blades should be replaced. In any case, since force application can vary during shaving, e.g., when shaving different areas of the face and from user-to-user, switching based on force application has severe limitations.
With the aim of conserving energy and eliminating the need for an on-off switch to control operation of an electric motor in a dry shaver, it has been proposed in U.S. Pat. No. 4,380,121 and U.S. Pat. No. 4,531,287, respectively, to actuate the motor in response to the cutter foil being placed into contact with and into close proximity to, the skin of a person holding the shaver. These dry shavers do not include vibration generators and they do not suggest any solution to the problem of discomfort associated with prior art vibrating safety razors. A hair dryer equipped with an infra red sensor or proximity sensor to control power supply to the fan and heating element is described in DE-A-1967734.